Now, to the case of the utah doctor about to go on trial for the murder of his wife, more than six years after her death. martin McNeil is accused of a bizarre plot to get his wife out of the way, to make room for his mistress. Aditi roy has the story. Reporter: Martin mcneil is at the center of an epic family drama about to play out in court next week. But the courtroom fireworks are flying. Lawyers fighting about which witnesses should be allowed to TESTIFY, including McNeil's daughter. The former utah doctor and mormon sunday schoolteacher is accused of killing his wife. His frantic call made on the day of her death, after the youngest child, eda, discovered her mother in the bathtub. MacNEILL'S OLDEST DAUGHTER Describes what eda told her. My dad told her to check on your mother. My dad stayed in the kitchen while she went into the bathroom and found her. Reporter: Macneill says he intentionally overdosed her, when she was recovering from a face-lift he compelled her to have. THIS WEEK, MacNEIL'S LAWYERS Argued that 12-year-old eda should not be allowed to take the stand. Was prosecutors allowed alexis to interview her. There's no evidence eda's testimony is tainted, even though MacNeil's older daughters think their father is guilty. We know he killed her mother. Reporter: During macneil's court appearances, they clutched their mother's pictures and stared down their father, while his lawyers professed his innocence. He has done some bad things in his life. Does that mean he's a murderer? No. Reporter: Also on the witness LIST, MacNEIL'S FORMER MISTRESS, Who moved into the family home, shortly after michelle's death. While the judge will allow some of his fellow inmates to take the stand, he has yet to allow whether to allow eda's testimony. A decision, in a trial that pits the once-powerful patriarch against his own family. For "good morning america," aditi roy, abc news, los angeles. So much to parse here. Dan abrams joins us. Among the many things to discuss here, another case we're seeing now, where the prosecution took many years to make its case before, in fact, charging the husband with murdering his wife, DR. MacNEIL HERE. Is it a tough case to make? I would reverse it and say i have no idea. They had enormous evidence against him for a long time. He was serving three years already, for stealing the identity of his adopted daughter. I don't think the authorities felt they had to rush this. But you're almost trying to -- you're saying, wait a sec. Exactly. This is one of the most bizarre cases I have covered. I do not say that lightly. Because of the amount of things they have against him. It seems everything in this guy's life was a lie. He lied about his degrees. He lied about having cancer. He stole his daughter's identity. It goes on and on and on. And then, you have this bizarre allegation that he's forcing his wife to have a face-lift because -- so he, as a doctor, can overdescribe her with drugs, kill her, so he can be with his mistress. And it won't be discovered. The authorities have had all of this for a long time. I can't give you an explanation why it took so long to charge him. This is a very strong circumstantial case. Lots of questions. It's only a two-hour show. We'll discuss more about this. Thanks very much. We're going to turn for another look at the weather.

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